We have all seen pictures in the media of sports stars huddled together taking a dip in an ice bath. The hugely successful Mo Farah, Jessica Ennis and Andy Murray have all used ice baths but why do they put themselves through the pain of cold water immersion (CWI) and does it have any beneficial (physiological or psychological) effect?

What is cold water immersion?

Cold water immersion (CWI) is thought to have originated from the practice of cryotherapy (low temperature treatments) for local injury (Brukner & Khan, 2000) and has been around for many years. It has grown in popularity over the last decade mostly due to the emergence of sports stars using them as a method of recovery.

CWI involves parts of the body (typically the lower half of the body) being submerged in cold water for a period of time. Many different techniques are used varying from a wheelie bin to a purpose made bath or pool. The temperature of the water is usually between 5˚c and 15˚c and periods of immersion range from a minute up to 24 minutes (Bleakley et al., 2012).

Why use CWI and how does it work?

CWI is used by many athletes looking to gain a competitive edge over their opponents by reducing muscle soreness and improving recovery. Theoretically, the quicker an athlete can recover, the quicker they can train/perform again and at a higher level.

Ice baths are believed to have the following effects:

Speed up recovery

Reduce inflammation

Decrease DOMS and stiffness

Make you feel good after

During vigorous exercise the muscle fibres become microscopically damaged. This triggers an inflammation response leading to swelling and delayed onset muscle soreness (DOMS). It is thought that the ice bath (low temperature) combats this by inducing vasoconstriction (narrowing of the blood vessels) flushing out toxins in the muscles, reducing local metabolism and reducing swelling and tissue breakdown. CWI immersion may also slow down nerve transmission speed and lead to a decreased perception of pain (Wilcock, 2006; Burgess & Lambert, 2010).

Where is the evidence?

There does appear to be some limited evidence that CWI reduces DOMS after muscle-damaging exercise at 24, 48, 72 and 96 hours compared with ‘passive’ (rest or no intervention) protocols (Bleakley et al., 2012; Higgins et al., 2012; Leeder et al., 2011, Ascensão et al., 2011). There is also some minimal evidence that showed participants felt better recovered/less fatigued immediately after CWI (Bleakley et al., 2012). Comparisons on perception of pain between CWI and contrast baths, warm water immersion, active recovery, compression and multiple immersions appear to be in favour of CWI (Bleakley et al., 2012). However, there are also studies that have reported CWI as having no beneficial effect (Goodall & Howatson, 2008; Sellwood et al., 2007; Howatson et al., 2009).

The fact that the differences found mainly appear to be a reduced perception of pain suggests that there may be a psychological (placebo) effect going on. It may be that because an athlete believes an ice bath will help them feel better that it does. Research into this is needed although blinding participants for a possible placebo effect of CWI would be very difficult.

It is important to note that the majority of evidence supporting the use of CWI comes from anecdotal sources. Generally, the research is of low quality and in many studies well founded conclusions cannot be drawn due to a lack of statistical significance and poor methodological quality. Also, the participants used are mostly untrained or elite young males making it hard to transfer any findings to the general population.

However, CWI does appear to be used well (anecdotally) by a variety of people with no known or reported consequences to health. Even if CWI is only a placebo effect, if it doesn’t harm an athlete and helps them to feel better recovered then perhaps it is worthy of use. Very often the psychological component of recovery is undervalued. If you do want to give the ice bath a try it is important to be aware of potential health risks (shock/hypothermia) due to prolonged exposure to cold temperatures. The ice bath certainly isn’t for the faint hearted or the unwell. If unsure, please check with a GP or medical professional before use.

Exactly how CWI works physiologically (if at all) remains unclear as there are very few studies showing any significant differences in biomarkers (clear physiological effects). Given that the inflammation process triggered after muscle damage is a part of adaptation to training it is important to be aware that limiting this effect by using CWI may have negative consequences for training.

At the moment there are no research driven guidelines for optimal/safe use of CWI and it is very difficult to draw valid and founded conclusions from the literature. All we can say is that there may be a beneficial effect of CWI in terms of recovery. Whether that is physiologically or psychologically and affects everyone remains to be proven. Good quality and reliable research is needed to set guidelines for best practice.

Take home messages

More research needed – better controlled studies with consistent methodologies to improve evidence and allow conclusions/implications for practice to be drawn.